Home networking is evolving into an environment in which people will be sharing photographs, music, video, data and voice among networked consumer electronics, personal computers and mobile devices throughout the home. Consumers will be able to stream video content from a personal computer or electronic device to flat panel high-definition television (HDTV) without the use of wires. A technology that will be implemented for enabling these capabilities is ultra wideband (UWB). UWB is a wireless technology designed for short-range, personal area networks.
The Federal Communications Committee (FCC) has mandated that UWB radio transmission can legally operate in the frequency range of 3.1 GHz to 10.6 GHz, at a transmission power of −41.25 dBm/MHz, having a minimum bandwidth of 500 MHz. Basically, UWB devices provide wide bandwidth transmission at very low signal power levels. Due to the low transmission signal power levels of UWB, transmission interference is a big issue. The interference can be from both non-UWB devices, and similar UWB devices.
FIG. 1 shows an example of an indoor broad band wireless communication network 100. The network 100 includes a high definition television (HDTV) monitor 110 networked with other devices, such as, a digital video recorder (DVR) 120, a digital video disk (DVD) player 140 and a computing device 130.
HDTV streaming video requires large bandwidths of information. Therefore, the networking of devices that include streaming HDTV must be capable of handling high bandwidths. Additionally, the devices of the network must be resistance to both self-interference and interference from other wireless communication signals. UWB wireless signals operate at very low power levels, making resistance to interference more difficult.
Personal home networks operating at very high data bandwidths can suffer from multi-path, which can constructively or destructively add to the main (typically, the shortest) transmission path. The multi-path signals are delayed copies of the signal of the main path multiplied by a random phase and amplitude, and cause inter-symbol interference (ISI). That is, an echo of a previously transmitted symbol can interfere with the reception of a present symbol.
The low transmission power levels of UWB networks make them susceptible to interference from like and unlike interferers. UWB devices within a home network are typically located proximate to each other, and as a result, can interfere with each other. Situations can include, for example, a UWB device being located very close to an undesired UWB source, while trying to communicate with a UWB device that is not as close as the undesired UWB device.
Diversity communication can be used to minimize the effects of multi-path and interference. For example, FIG. 2 shows a receiver 210 that includes two receiver antennas 222, 224. One of the two antennas 222, 224 is connected to a receiver chain that includes a channel filter 230, a low noise amplifier (LNA) 240, a frequency down-converter 250, an automatic gain controller (AGC) 260, a base band filter 270 and an analog to digital converter (ADC) 280. Generally, signals S1, S2 received by each of the two antennas 222, 224 have travel different transmission paths. Therefore, each of the received signals S1, S2 is typically subjected to different degrees of multi-path and interference. The receiver 210 can select one of the signals S1, S2 for reception. Essentially, base-band processing includes selecting each antenna individually based upon signal power and/or channel response measurements. Typically, the antenna providing the most desirable signal power and channel response is selected. However, the selection can be based upon a combination of several received signal parameters, such as, signal power, channel delay spread and channel frequency selectivity.
It is desirable to have an apparatus and method for a wireless diversity reception that can be implemented with low-cost devices, and can effectively increase the signal to noise, and/or the signal to interference ratios of received signals.